whether to keep aspect ratio
Deprecated: Use gtk.picture.Picture.setContentFit instead. If still used, this method will always set the propertyGtk.Picture:content-fit property to gtk.types.ContentFit.Contain if keep_aspect_ratio is true, otherwise it will set it to gtk.types.ContentFit.Fill.
If set to true, the self will render its contents according to their aspect ratio.
That means that empty space may show up at the top/bottom or left/right of self.
If set to false or if the contents provide no aspect ratio, the contents will be stretched over the picture's whole area.